Water heater controls and safety device therefor



Sept 17, 1957 2,806,652 WAT QHEATER CONTROLS AND SAFETY DEVICE THEREFOR I Filed Oct. 15, 19541 T. T. ARDEN ET AL INVENTORS Tho/{2m 7. fli'dell mzd War I Jackson.

THEIR ATTORJVZY Sept. 17, 1957 T. T. ARDEN ETAL' 2,806,652

WATER HEATER CONTROLS AND SAFETY DEVICE THEREFOR Filed 001;. 15. 1954 2 Sheets-Sheet 2 m T 14 gVENTORS omas 1'' e12 wad 27- 3715665!!! F (Imam.

United States Patent D p WATER HEATER CONTRQLS AND SAFETY DEVICE THEREFOR Thomas Tracy Arden, Santa Ana, and Wilbur Fred lackson, Compton, Califi, assignors to Robertshaw-Fuiton Controls Company, Greensburg, Pa., a corporation of Delaware Application October 15, 1954, Serial No. 462,434]

4 Claims. (Cl. 2362l.)

This invention relates to combination controls for gas eous fuel burners and more particularly to devices for controlling the flow of fuel to the main burner in the event of overheating to a high temperature beyond which danger to the appliance structure would be present.

In appliances of this general character, there is provided a main fuel burner, a pilot burner, a safety device in the form of a thermal element located adjacent to the pilot burner to be heated thereby for actuating a valve member controlling the fuel flow to the main burner and a thermostat responsive to predetermined water temperatures for controlling fuel flow to the main burner. In the event of flame failure at the pilot burner, sufficient cooling of the thermal element will cause the closing of the valve member and a consequent shuting-olf of the fuel fiow to the main burner.

One of the major problems confronting the designers of these appliances, is the controlling of the water temperature in the top portion of the tank during the period of frequent withdrawals of water. During such periods the water temperature in the top portion of the tank quite often increases to unsafe values even though the thermostat is functioning properly. In order to avoid creating this unsafe Water temperature condition, commonly re ferred to as stacking, it has been customary to install a high temperature gas shut-off device of the manual reset type. The purpose of this device is to shut off fuel to the main burner when the temperature in the top portion of the tank approaches the unsafe limit. Such devices prevent the occurrence of high temperatures, however, they do have the disadvantage that the control has to be manually reset and the main burner relighted again before the hot water service could be restored. A similar safety device has been incorporated into these appliance controls for shutting down the operation of the appliance in the event of overheating and this device has taken the form of a thermostat having a thermally sensitive element located in the top portion of the tank, which is adapted to shut-off the flow of fuel to a pilot burner thereby shutting off the fuel supply to the main burner- The disadvantage in this type of system is similar to that of the high temperature gas shut-off device in that thecontrol has to be manually reset and the pilot burner reignited. v

The present invention is particularly adapted, although. not limited, for use with gas-burning water heaters and the like wherein water temperatures are to be controlled within precise limits. A primary thermostatic device controlling fuel flow to the main burner is provided and is preferably of the rod-and-tube type having a temperature adjusting dial located on the front face of a control. body for ready 'access by the user. A thermally sensitive element is provided and located to respond to the temperature of the water at the top portion of the tank and is connected to a dual actuated control valve adapted to control the flow of fuel to the main burner in response to a predetermined high temperature. One phase of this 2,806,652 Patented Sept. 17, 1957 control will shut 01f gas to the main burner only, and will permit the pilot burner to continue burning and this action to take place regardless of the fact that the primary thermostatic control is still calling for heat; and the second phase acting as an over-temperature safety device will shut ofl gas to the burner in the event of a continued build up of temperature beyond the safe limit afiorded by the first phase of the control.

An object of the present invention is to insure proper water heater temperature build-up without complete shutdown of the control system.

Another object of the present invention is to prevent the occurrence of an unsafe water temperature without shutting down the burner control system when such a temperature is caused by the stacking phenomena.

Another object of the present invention is to assure complete shutdown of the flow of gas to the main burner in case the temperature continues to rise due to a failure of the primary thermostatic control.

Another object of the invention is to utilize a high temperature safety shut-off control which may be used in conjunction with all existing types of thermostatic water heater controls.

With these and other objects and advantages in view, a preferred embodiment of the invention is illustrated in the accompanying drawings wherein:

Fig. l is a side elevation of a water tank and heater partly broken away to show a control system embodying the present invention; and

Fig. 2 is an enlarged sectional view taken along line 11-11 of Fig. 1. 7

Referring more particularly to the drawings, there is illustrated in conjunction with a Water tank 10 of a conventional type water heater, a main burner 12 in heating proximity thereto, a pilot burner 14 for igniting the main burner 12 and a thermocouple 16 located adjacent the pilot burner 14. As is customary in such devices, a suitable pipe connection 18 is provided to convey fuel from a combined thermostat and automatic pilot control indicated generally by the reference numeral 20 to the main burner 12. The combined thermostat and automatic pilot control 20, may be of any suitable form and preferably is of the type shown and described in detail in U. S. patent to Jackson No. 2,658,515 issued on November 10, 1953.

The thermostatic control 20 is responsive to the water temperature in the tank 10 and is preferably of the type having a rod-and-tube temperature sensitive element 22 extending into the same in thermal contact with the water contained therein. The sensitive element 22 is operatively connected through appropriate means to a main valve (not shown) for controlling the supply of fuel to the main burner 12 and has direct connection to a source of fuel supply (not shown) by a pipe 24. In operation, the element 22 responding to minimum and .maximum temperatures of the water being heated by the main burner 12 operates to open and close the main valve thereby controlling the flame at the main burner to maintain the temperature of the water Within close limits. A number of such thermostats are in common use today and are well understood in the art, therefore further details and description are unnecessary.

Interposed in the connecting pipe 18 between the thermostatic control device 20 and the main burner 12 is a high and over-temperature safety control device indicated generally by the reference numeral 26.

The safety control device 26, as shown in Fig. 2, is housed in an elongated casing 28 of substantially rectangular form in plan having side walls 30, 32 and end walls 34, 35. An internally threaded hollow boss 36 is formed on the end wall 34 for the reception of one end of pipe 18 and provides an inlet for conveying fuel from the pipe 18 into a valve chamber 40 formed within the casing 28.

The valve chamber- 40 is formed interiorly of the casing 28 by a longitudinally extending wall 42 integral with and projecting from the end wall 34 and an annular wall 44 formed on one side of the wall 42. The annular wall 44 is internally threaded for the reception of an annular valve seat member 48 having an axial hollow boss 50 formed therein and providing a bearing for a hollow valve stem 52 for relative slidable movement therein. A disc valve member 54 is mounted on the valve stem 52 for movement therewith between open and closed positions relative to the seat 48. The valve member 54 is normally biased toward the seat 48 by means to be described more fully hereinafter. Suitable ports 56 extend longitudinally through the valve seat 48 to provide communication between the valve chamber 40 and a gas outlet 58 located in one of the walls of the casing 28 and adapted to be connected to the other end of the pipe 18.

The hollow valve stem 52 contains an override mechanism comprising a plunger 60 and biasing spring 62 which serves to urge a collar 64 on the plunger 60 into engagement with a bushing 66 closing the inner end of the hollow valve stem 52. The plunger 60 projects through the bushing 66 for operative engagement with a clicker mechanism 67 of the conventional type including a thrust element 68 which is movable within the annular valve .seat 48 for imparting snap-action movement to the plunger 60 and the valve member 54.

Thermally sensitive actuating means is provided for operating the valve 54 between controlling positions through the clicker mechanism 67 and, in this embodiment, is of the hydraulic or liquid type being filled with a thermally expansible fluid which is adapted to be subjected to the temperature of the water being heated. Such means includes a thermally sensitive element 70 mounted to project into the water tank in thermal contact with the water contained therein and has the usual capillary tube 72 in communication with a bellows member 74. A rod 73 projects from the bellows member 74 and is slidably mounted in an opening formed in a mounting post 75 secured to a wall of the casing 28. The rod 73 has a conical tip 77 for engagement by an adjusting screw 78 threaded into a tapped bore 76 to afford a means for longitudinal adjustment of the bellows member 74 for a purpose to be described hereinafter. The screw 78 also serves to prevent axial displacement of the rod 73 and, consequently, one end of the bellows member 74 after adjustment.

In this invention, motion transmitting means is provided between the bellows member 74 and the valve member 54 and is divided into two lever mechanisms herein referred to as phases. In the operation of the first phase of the transmitting means, the bellows member 74, in response to a first predetermined temperature, actuates the valve member 54 through the clicker mechanism 67 independently of the second phase. In the operation of the second phase, the bellows member 74, in response to a second predetermined temperature, serves to maintain the valve member 54 in a closed position regardless of subsequent thermal conditions of the thermal sensitive element 70, once the first phase has moved the valve member 54 to a closed position.

The first phase or lever mechanism, indicated generally by the reference numeral 80, functions as a high-temperature control device and takes the form of an elongated lever member 81 having an intermediate portion 84 underlying the bellows member 74 to be engaged by a thrust button 82 carried by the bellows member 74. The lever 81 extends along the underside of the wall 42 and is pivoted on a pin 87 mounted in a lug 86 which is secured to the wall 42 adjacent to the end wall 34.

A spring 88 having one end secured to the interior of the wall 32 and its other end abutting normally biases the lever 81 in a clockwise direction and into contact with the thrust button 82. A transmission button 90 is slidably received in an opening in the wall 42 for engagement with the thrust element 68 of the clicker mechanism 67 for operating the same as will hereinafter be apparent. The temperature at which the valve member 54 will be operated may be adjusted by means of the adjusting screw 76 by manually rotating the same relative to the wall 30.

The interior of the casing 28 opens into the valve chamber 48 defined by the annular wall 44 and the wall 42. A flexible sealing disc 94 extends across the open end of the annular wall 44 for preventing communication between the chamber 40 and the interior of the casing 28. Thus, passage of fluid from the valve chamber 40 into the casing 28 is prevented.

The sealing disc 94 carries a spring retainer 96 secured thereto by an axially located plug or rivet 98. A coil spring 100 is operative between the valve member 54 and the retainer 96 and serves to bias the valve member 54 toward the seat member 48.

The second phase of the motion transmitting means, indicated generally by the reference numeral 101 and herein referred to as an over-temperature safety device, is employed to lock the valve member 54in a closed position in the event of additional expansion of the bellows 74 caused by overheating of the water in the tank 10. To this end, a lever member 102 overlying the valve member 54 and the bellows 74 is pivoted intermedate its ends on a pivot 104 projecting from a wall of the casing 28 into the interior thereof. One end of the lever member 102 carries a latching arm 106 which is operatively engageable with a locking arm 108 formed on the end of the lever 81 adjacent the bellows 74. The extreme tips of the arms 106, 108 are beveled at 110, 112 respectively for a purpose to be described hereinafter. At the end of the lever member 102, remote from the pivot 104, and operative axially of the valve stem 52 is a thrust button 114 which is received in a retaining cup 116 secured to the sealing disc 94 by the rivet 9'8. A coil spring 118 having one end secured to the interior of the wall 30 and its other end abutting an end of the lever 102 serves to bias the lever 102 in a clockwise direction and the valve member 54 into a closed position. The biasing effect of the spring 118 however, is prevented from rotating the lever 102 in a clockwise direction by the latching engagement of the latching arm 106 with the locking arm 108, therefore the valve member 54 is normally in an open position by reason of the relatively large bias effect of the spring 88 exerted on the transmission button 90. This bias effect is large enough to overcome the force exerted by the spring 100 which tends to seat the valve member 54 on the valve seat 48, however, it is not large enough to overcome the bias of the spring 118 once the latching arm 106 becomes disengaged from the locking arm 108.

In the normal operation of the high-temperature control mechanism 80, the bellows 74 is allowed to expand or contract within certain limits of temperature within the tank 10. The expansion of the bellows 74 causes the lever 81 to rotate about its pivot in a counterclockwise direction and the arms 106, 108 are adapted to slide with respect to each other during the normal build-up of temperature in the water tank 10. In the event that the temperature within the tank reaches a certain upper limit, say up to F., the counterclockwise rotation of the lever 81 permits the downward movement of the button 90 as viewed in the drawing and allows the clicker mechanism 67 to move the plunger 60 downward. Such downward movement permits the coil spring 100 to seat the valve member 54 thereby shutting oil the fuel supply to the main burner 12. With the valve member 54 in a closed position, any further increase in temperature above 190 F. will cause still further expansion of the bellows 74 and counterclockwise rotation of the lever 81 so that the arm 106 will disengage itself from the locking arm 108 causing the lever member 102 to rotate in a clockwise direction under the bais of the coil spring 118. This operation in effect locks the valve member in a closed position.

To reset the levers 81 and 102 in their original operating position, a resetting means is provided on the casing 28 and takes the form of a reset button 120 reciprocally mounted in an opening in the side wall 30 adjacent the latching arm 106. A flange 122 carried by the reset button 120 serves to anchor one end of a coil spring 124 at one end thereof. An enclosure housing 126 serves to anchor the other end of the spring to hold the reset button 120 in its outermost position. Upon depressing the button 120, the extreme tip 128 thereof abuts a projection 130 on the lever member 102 beyond the latching arm 106 thereby rotating the member 102 in a counterclockwise direction. The bevel surface 110 is thereupon caused to slide on the bevel surface 112 and causes the latching arm 106 to ride over the bevel 112 and be positioned once again in a locking position with respect to the lever 84.

Operation The safety control device 26 is shown in the drawing in a position for preventing fuel flow to the main burner 12.

Assuming that the valve member 54 is in open position and the rod-and-tube element 22 calls for heat. The valve associated with the thermostatic control 20 is now open to allow fuel flow to the control device 26 through the opening 33, chamber 40, past the valve seat 48 and through the fuel outlet 58 to the main burner 12 which will be ignited by the pilot burner 14. Normally, the rod-and-tube element 22 is adjusted to close the thermostatic control 20 at 140 F., however, in the event of excessive withdrawal of water from the tank 10, the incoming cold water tends to cool the element 22 and hold the main valve open so that the main burner continues to heat the water in the tank causing the temperature of the water at the top of the tank to build up excessively.

In the first stage of operation of the safety control device 26, the increase in temperature at the top of the tank causes the thermal fluid in the thermally sensitive element '70 to expand the bellows 74 and cause the lever 81 to be rotated in a counterclockwise direction against the bias of the spring 88. The transmission button 90 is then free to slide downwardly, as viewed in the drawing, permitting the clicker mechanism 67 to snap in a direction which will allow the valve member 54 to close against its seat 48, thereby shutting ofi the flow of fuel to the main burner 12. Conversely, on the cooling of the element '70, the bellows 74 will contract permitting the spring 83 to rotate the lever 81 in a clockwise direction permitting the clicker mechanism 67 to move the valve 54 to its open position and establish fuel flow to the main burner 12 which will be ignited by the pilot burner 14. During this stage of the operation of the safety control device 26, the locking arm 108 is in contact with and slides along the latching arm 106, thus preventing the rotation of the lever member 102.

It is to be noted that the high-temperature control mechanism 80 shuts off the fiow of fuel to the main burner only, and permits the pilot burner 14 to continue burning. This action takes place regardless of the fact that the thermostatic control 20 is still calling for heat. During this stage of operation of the safety control device 26, by maintaining a flame at the pilot burner 14, the necessity of resetting the thermostatic control 20 is eliminated.

For extraordinary conditions, for example, in the event of malfunctioning of the thermostatic control 20 whereby fuel flow to the main burner 12 cannot be shut ofi or properly controlled and the consequent continued heating of the water causes the temperature of the water at the top of the tank to exceed 190, the cooperation between the high-temperature control mechanism and the bellows 74 causes an additional counterclockwise rotation of the lever 81 even after the temperature in the vicinity of the sensitive element 70 has initiated the closing of the valve member 54. 7 Such rotation serves to disengage the locking arm 108 from the latching arm 106 and causes the clockwise rotation of the lever member 102 under the bias of the spring 118. The thrust button 114, thus driven, impinges upon the rivet 98 to force the same into operative engagement with the valve stem 52 and lock the valve member 54 into engagement with its seat 48. As previously indicated, the valve member 54 was moved to its closed position by the initial expansion of the bellows 74 during the first stage of operation of the safety control device 26. The subsequent expansion of the bellows 74 serves to lock the valve 54 in its closed position so that the opening thereof can only be accomplished by the manipulation of the button to reset the latching arm 106 and the locking arm 108. Such subsequent locking of the valve member 54 can be maintained regardless of whether the thermally sensitive element 70 is operating to move the valve member to open position due to provision of the override connection within the hollow valve stem 52. Thus, the bias of the override spring 62 is overcome upon inward movement of the plunger 60 and, due to the strong bias exerted by the coil spring 110, the plunger 60 will move relatively to the hollow stem 52 during compression of the override spring 62.

The over-temperature safety device of this invention provides a means for preventing the recycling of the hightemperature control mechanism 80 and the flow of fuel to the main burner in the event that temperatures in the upper portion of the water tank 10 rise above F. The safety device is preferably set at the factory to operate at about 210 F. As stated previously, this feature completely shuts down the heating system and is usually not placed in operation unless there is a malfunctioning of the thermostatic control 20 such that closing of the main valve associated therewith is prevented and the main burner continues to heat the water in the tank. In this case, the high-temperature control device 80 will maintain the temperature of the water at the top of the tank at approximately 190. Under such condition, this mechanism actually serves as a primary heater control means. However, subsequent increases of temperature will probably occur to place the over-temperature safety mechanism 101 into operation for complete shutdown of the heating system.

It will be understood that many changes may be made in the details of construction and arrangement of parts to accomplish the purposes of this invention without departing from the scope of the invention as defined in the appended claims.

We claim:

1. In a temperature control system for a water heater and the like having a tank and a burner for heating the contents of the tank, a source of fuel supply for the burner, the combination of first thermally operable means responsive to temperature variations in the lower portion of the tank, first valve means operable between open and closed positions by said first thermally operable means for controlling the supply of fuel to the burner to maintain a predetermined normal temperature in the contents of the tank, second thermally operable means responsive to temperature variations in the upper portion of the tank, second valve means operable between open and closed positions by said second thermally operable means for controlling the fuel supply independently of said first valve means, said second valve means being initially operable to said closed position in response to a predetermined higher temperature than said normal temperature, and safety means operable by said second thermally op erable means for maintaining said second valve means in said closed position responsive to a temperature in excess of said predetermined higher temperature.

2. In a temperature control system for a water heater and the like having a tank and a burner for heating the contents of the tank, a source of fuel supply for the burner, the combination of first thermally operable means responsive to temperature variations in the lower portion of the tank, first valve means operable between open and closed positions by said first thermally operable means for controlling the supply of fuel to the burner to maintain a predetermined normal temperature in the contents of the tank, second thermally operable means responsive to temperature variations in the upper portion of the tank, second valve means operable between open and closed positions for controlling the fuel supply independently of said first valve means, lever means operably engageable with said second valve means and biased for urging said second valve means toward said open position, said second thermally operable means being operatively engageable with said lever means for overcoming said bias and causing operation of said second valve means to said closed position, said second valve means being initially operable to said closed position in response to a predetermined higher temperature than said normal temperature, and safety means operably associated with said lever means and said second thermally operable means for maintaining said second valve means in said closed a position responsive to a temperature in excess of said predetermined higher temperature.

3. In a temperature control system as claimed in claim 2 wherein said safety means includes a latching device for said lever means operative for releasing said lever means'only when said second thermally operable means responds to said excess temperature.

4. In a temperature control system as claimed in claim 3 wherein resetting means are provided for manual operation of said latching device to latch said lever means upon cessation of said excess temperature.

References Cited in the file of this patent UNITED STATES PATENTS 1,108,772 Meacham Aug. 25, 1914 1,421,692 Hutchinson July 4, 1922 1,898,703 Williamson Feb. 21, 1933 2,032,447 Stack Mar. 3, 1936 2,102,752 Schoenfeld Dec. 21, 1937 2,305,068 Douglass Dec. 15, 1942 2,354,755 Johnson Aug. 1, 1944 2,383,401 Mantz Aug. 21, 1945 2,387,792 Holmes Oct. 30, 1945 2,576,675 Drow Nov. 27, 1951 

